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To get to the bottom of your question can i ask you:
Have you check the transmission fluid level?
Have you had any diagnostic check carried out on the transmission?
No I din't check the oil level but,
There be a warning if the level is to low.
There was not any worning, and the problem will appear more then two times during the driving every time when the transmission have to change from 3 to 4 geer
starting and stopping the engine more then ten times a day
Once appear worning: speed sensor failure
If the fluid level is ok then you could be looking at a speed sensor or a temperature sensor fault.
The only option is to have the fault codes read from the gearbox and engine control units, this will give you a i dear of what sensor requires attention.
You can have the fault codes read by a specialist or a dealer.